[VHFcontesting] [VHF] Antenna Coupling Issues

[Les Rayburn]

Along with Stan, several folks have mentioned using tight bandpass filters 
on both TX and RX. I looked over DCI's filters today, and saw a few that 
might fit the deal. I'm curious has to what others are using.

The bandpass filter option appeals to me as I think it would provide the 
added benefit of reducing my interference levels, and providing some 
additional protection for the pre-amps and front ends. I can't imagine that 
I'm ever going to even seriously consider running more than 200-300 watts on 
any band given the indoor antennas. It will be easy to become an "alligator" 
and certainly will only cause issues with TVI/RFI, including the potential 
to interfere with the President of the HOA who lives next door.

So, sources? Prices? Anything to avoid?

73,


Les Rayburn, director
High Noon Film
100 Centerview Drive Suite 111
Birmingham, AL 35216-3748
205.824.8930
205.824.8960 fax
205.253.4867 cell

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From: "Stan, W1LE" <stanw1le at verizon.net>
Sent: Friday, July 11, 2008 11:08 AM
To: "Les Rayburn" <les at highnoonfilm.com>
Subject: Re: [VHF] Antenna Coupling Issues

> Hello Les,   My comments are added.....
>
>
> Les Rayburn wrote:
>> 1. At what power levels (typically) does this begin to be an issue?
>>
> Too many variables that need controlling to comment, you are on thin ice.
> destruct level of the preamplifier,
> preamp isolation (filtering) for out of band signals,
> TX power levels,
> quality of coax being used, braided shields leak, solid shields like solid 
> copper on superflex or hardline are betrter,
> Bypass relay isolation,
> antenna proximity, near filed issues.
> polarizations used,
> Coaxial cable losses,
> etc.
> etc.,
>
>> 2. Are there steps that I can take to minimize the coupling, and protect 
>> the
>> pre-amps and radios?
>>
> Coupling is proximity. Either I disable all preamplifiers not used, except 
> for the band I am playing on or
> I have tight bandpass filters and leave the preamp on for other RX bands.
> Tight bandpass filters for RX AND TX.
> Another alternative is to disable all preamps on ALL bands,  when I 
> transmit on any band. including HF.
>
> All preamplifiers default to a bypass mode, when the system is not used.
>> 3. What do rovers in similar situations do to prevent problems?
>>
>
> Rovers usually go thru a few preamplifiers until they take the previously 
> mentioned actions.
>
>
> Stan, W1LE   Cape Cod
>
>
>
>
> ZZZZZz
>>
>>
>>
>
>